Naturally occurring colloids such as humid acids represent types of polyelectrolytes which affect the environmental quality of water. Artificial polyelectrolytes are often used as flocculants for treatment of colloidal water as well as water which contains suspended materials. Anionic polyelectrolytes, such as potassium poly (vinyl sulfate) and polystyrenesulfonate are, respectively, used as dispersants for concentrated ceramic slurries and that for coal water mixtures-the latter of which represents a promising alternative fuels. As a result, urgent needs have developed for rapid and sensitive analytical methods for the detection and measurement of polyelectrolytes in environmental water and for the process control of dispersants in concentrated ceramic slurries and coal water mixtures. In this paper, we will describe polyelectrolyte- and surfactant-sensitive sensor based on quartz crystal microbalance (QCM) method for the determination of polyelectrolytes and surfactants. The response of QCM sensor based on the Au film immobilized with a SH(CHィイD22ィエD2)ィイD210ィエD2COOH to a cationic polyelectrolyte was examined. The sensor did not respond to cationic polyelectrolytes in the concentration range from 10ィイD1-5ィエD1 to 10ィイD1-2ィエD1 M. Furthermore, QCM sensor based on the Au film immobilized with SH(CHィイD22ィエD2)ィイD23ィエD2NHィイD22ィエD2 HCl did not respond to anionic polyelectrolytes in the concentration range form 10ィイD1-5ィエD1 to 10ィイD1-2ィエD1 M.